In recent years, x-ray inspection has become increasingly common in certain segments of the food industry. In particular, because of the ever-increasing emphasis on food safety, processed foods, including e.g., products that are packaged in cans, bottles, or jars, are typically x-ray inspected.
X-ray inspection is superior to traditional metal detection technology for the detection of metallic contaminants, and is also effective for detection of non-metallic material such as e.g., bone, glass, wood, plastic, and rocks. Indeed, technological advances in the areas of high voltage power supplies, solid-state detectors, and computation power and speed have made x-ray systems more affordable, reliable, and easier to use while improving image quality and detection capabilities. A variety of improvements in sensor technology have improved resolution, including CsI crystals and improved CCD arrays.
In a typical linescan x-ray machine, a two dimensional image of an object or objects are created using hundreds or thousands of detectors, e.g., photodiodes overlaid with phosphor or semiconductor crystals, placed in a row perpendicular to the direction of sample flow. As the sample moves between the x-ray source and the detector array at a fixed rate, the output of the photodiodes are repeatedly scanned at a rate synchronized to the speed of the sample. The two dimensional image is then constructed row by row. Creation of the image is thus dependant on the motion of the sample across the line of detectors. Most high-speed applications employ a side view arrangement, as opposed to a top view system since this way the conveyor belt is not included in the image.
Forming a two-dimensional image requires timing the scanning of the detector array to the motion of the sample and tracking the output of each individual photodiode for each scan. Thus, two dimensional x-ray imaging is complicated, and adds a great deal of cost and complexity to the sorting/inspecting apparatus. Indeed, linescan x-ray machines for food inspection are bulky and expensive and their incorporation into an existing food processing line is often disruptive. What's more, it is often the case that a two dimensional image is not required to accomplish the inspection/sorting task. Thus the degree of complication and sophistication embodied by linescan x-ray machines is frequently unnecessary.
Therefore, what is needed in the art is an effective, less expensive and less complicated x-ray based sorting/inspection device. Fortunately, as will be clear from the following disclosure, the present invention provides for this and other needs.